This invention relates to improvements in the production of liquid iron in an electric furnace of melter.
It is well accepted that there are a number of methods and arrangements relating to melting iron bearing materials, which utilise iron bearing materials in a partially reduced state. This then means that a reasonably substantial amount of further reduction (and the consequential use of further power) must take place in the furnace or melter which is used for the production of liquid iron. As a result this requires high energy and power consumption which can be both a practical and economic problem. In addition, when such partially reduced materials are used in the production of liquid iron, further reduction of such iron bearing materials has shown that the carbon content of the resultant liquid iron has been low and in some cases insufficient for further satisfactory processing.
Further, in methods and arrangements used up until this time, where partially reduced iron bearing materials have been used, there has been a problem with the type of iron bearing materials or ores that could be used. Thus, because of the difficulties inherent in using some iron bearing materials (particularly when in a partially reduced state), time and effort has been required in the selection of the iron bearing materials, or feedstock. This is because certain materials (such as for example titaniferous iron sand) have not been able to be effectively used in the production of liquid iron using methods and arrangements used up until this time. In some methods used up until this time, the use of such iron bearing materials has made it very difficult (if not impossible) from a practical point of view, to accurately and adequately control the content and nature of the resultant liquid iron.
In addition, there has been a real problem in using fine iron bearing material. Where partially reduced material is used in a furnace or melter, substantial amounts of gases are formed during reduction within the furnace, and below the surface of the slag, formed on top of the liquid iron. The gas thus evolved, is the result of the only partially reduced nature of the iron bearing material and has up until this time, caused explosions and slag blows and boils within the furnace or melter. Where fine iron bearing material has been experimented with, it has been found inappropriate in such processes involving the use of partially reduced material. The fine iron bearing material or ore forming a slag, presents problems in that the gases below the surface will easily pass up and rupture through the slag of the fine material, this again causing explosions and slag blows and boils within the furnace or melter. This has detracted from the efficiency and general operation of methods and arrangements utilising partially reduced material, as used up until this time.
By way of example only, in methods and arrangements used up until this time, those skilled in the art would have generally been reluctant to utilise partially reduced iron bearing material which included by way of example only, between 10% and 20% (by weight) below 6 mm in size. It will be appreciated therefore, that methods and arrangements used up until this time have not been able to take advantage of a large amount of iron bearing material, due to the deficiencies and problems associated with the methods and arrangements used and known up until this time.
As referred to hereinbefore, a further and very real problem associated with methods and arrangements used up until this time, is that where only partially reduced iron bearing material is used in a furnace or melter, the energy consumption is high and a large amount of gas is formed. Thus, not only is this a problem from an economic and power supply point of view, but the carbon content of the resultant liquid iron (resulting that is from the electric furnace) has in numerous cases been insufficient or at least unsatisfactory, for further processing or use.
It is an object of this invention to provide a method and arrangement for producing liquid iron in an electric furnace or melter which overcomes or at least minimises the problems encountered up until this time.
It is a further object of this invention to provide a method and arrangement for the production of liquid iron in an electric furnace or melter which is straight forward and efficient in operation.
Other objects of this invention will become apparent from the following description.